Performance Of Surface Plasmon Resonance Research Articles

Trends in surface plasmon resonance biosensing: materials, methods, and machine learning.

Surface plasmon resonance (SPR) proves to be one of the most effective methods of label-free detection and has been integral for the study of biomolecular interactions and the development of biosensors. This trend delves into the latest SPR research and progress built upon the Kretschmann configuration, a pivotal platform, and highlights three key developments that have enhanced the capabilities of the technique. We will first cover a range of explorations of novel plasmonic materials that have shaped SPR performance. Innovative signal transduction and collection, which leverages traditional materials and emerging alternatives, will then be discussed. Finally, the evolving landscape of data analysis, including the integration of machine learning algorithms to navigate complex SPR datasets, will be reviewed. We will also discuss the implementation of these improvements that have enabled new biosensing functions. These advancements not only pave the way for enhanced biosensing in general but also open new avenues for the technique to play a more significant role in research concerning human health.

D-Shaped PCF With Quasi-Sinusoidal Surface Topography for Dual-Polarization and Enhanced Performance Surface Plasmon Resonance Sensor

D-Shaped PCF With Quasi-Sinusoidal Surface Topography for Dual-Polarization and Enhanced Performance Surface Plasmon Resonance Sensor

Er2O3 doped zinc borosilicate glass substrate: Impact of doping to the structural, optical and surface plasmon resonance performance

Er2O3 doped zinc borosilicate glass substrate: Impact of doping to the structural, optical and surface plasmon resonance performance

Investigation of a highly-sensitive aluminum-based plasmonic device using antimonene for sensing applications

Aluminum (Al) has gained popularity for surface plasmon resonance-based applications due to its affordability and compatibility with CMOS technology at the nanoscale. Over angle-interrogation mode, plasmonic interactions occurring at the metal-dielectric junction, are the outcomes of the attenuated total internal reflection phenomenon. Modified Al-based Kretschmann configuration results in phase-matching conditions that are seen as resonant points in the reflection characteristics. In our work, we have engineered an Al-based plasmonic device utilizing Antimonene as a 2D nanomaterial for bio-sensing purposes in the Near-Infrared (NIR) spectral domain. The study investigates the performance of Surface Plasmon Resonance (SPR) based refractive index sensor using different 2D nanomaterials with an optimized Al thickness of 30 nm. A comparative analysis of Al-based Kretschmann configurations in the presence of Graphene, Black Phosphorus, MXene, and Antimonene is presented using engineered intermediate layers. It is observed that the Al-antimonene-based plasmonic device exhibits improved sensing parameters in the NIR optical window.

Study the Optical Properties of Noble Metal (Au, Ag, and Cu) Thin Film Biosensors Based on Surface Plasmon Resonance Performance by a Simulation Program

In this work, we studied the effect noble metal thicknesses, namely gold (Au), silver (Ag), and copper (Cu) on the surface plasmon resonance (SPR) characteristics for sensitive optical sensor and biosensor applications. SPR spectra for Au, Ag and Cu were widely studied in the Fresnel equation to calculate the total reflection, the wavelength ([Formula: see text] range from 500 nm to 700 nm with the angle of incidence ([Formula: see text] ranging from 0∘ to 90∘ and thickness of the film ([Formula: see text] reaching from 30 nm to 70 nm. Analysis simulation (in MATLAB) has been made for SPR of three metals placed on the N_LASF9 glass prism and the sensing medium is the air. The properties of the angle of resonance [Formula: see text] have been calculated from plotted reflectance via incident angle [Formula: see text]. The results give efficient detection in a change of reflection ([Formula: see text] and full half width maximum FWHM. The minimum reflection was obtained (0.003 a.u.) at wavelength 700 nm and thickness [Formula: see text]= 50 nm for gold Au at [Formula: see text] = 0.0. The best FWHM was recorded at the wavelength (500 nm) at thickness (70 nm) for silver at [Formula: see text] = 0.0, which was equal (0.1 nm).

Effects of thickness and roughness on plasmonic characteristics of gold thin films deposited on polished optical fiber

The thickness and roughness of metal layers substantially affect the performance of surface plasmon resonance (SPR)-based sensors. The deposition methods, control parameters, and substrate characteristics influence the layer thickness and roughness. This study investigates the SPR characteristics of a polished optical fiber surface coated with gold (Au) metal of different thicknesses. The Au layer is deposited via the thermal evaporation method, and its thickness is varied by controlling the deposition time (3–6 min). A proportionality relationship between thickness and deposition time is observed. Island-shaped structures in gold (Au) morphology are formed due to low adhesion to the substrate. The shape of this island creates gaps in the layer, causing scattering. In addition, the roughness on the gold surface triggers the Localized Surface Plasmon Resonance (LSPR) phenomenon. As a result, the measured dielectric characteristics differ from the reference. The SPR curve calculation simulation was carried out based on reference optical parameters and measurement results by an ellipsometer, which were then compared with experiments. The obtained results show that the substrate roughness, morphology, and thickness of the Au layer play an essential role in determining the characteristics of the SPR curve in a fiber optic plasmonic sensor. As a result, in basic experiments, the sample with an Au thickness of 27.37 nm (deposition time = 3 min) shows better characteristics (half-maximum full width, minimum transmittance, and resonance wavelength) compared with the sample with an Au thickness of 53.97 nm (deposition time = 4 min), Although 53.97 nm is the optimal thickness from the simulation using reference optical parameters (smooth substrate surface and smooth gold layer).

A Hybrid Design for the Functional Assay of LvLRRm (Protein Containing LRR Domain) of the White Leg Shrimp, Litopenaeus vannamei

In the crustacean immune system, leucine-rich repeat (LRR) is one of the major structures for recognizing pathogen-associated molecular patterns (PAMPs). LRR domain-containing proteins belong to the LRR family, which is a large group of proteins with more than 6000 genes in the database. They are involved in very diverse physiological functions, mainly by interacting with other proteins. In a previous study, the LvLRRm, a transmembrane protein containing only LRR domain, was identified in the white leg shrimp, Litopenaeus vannamei. Its versatile role in performing multiple immunomodulation activities has been reported. However, there is still a lack of research on its efficient function at the protein level. To investigate its interactions with other proteins, we applied a convenient method called the ‘Hybrid LRR technique’ to produce a recombinant LvLRRm. The LvLRRm and hagfish’s variable lymphocyte receptors (VLRs) fragments were fused to the conserved LxxLxLxxN motif while retaining the β-strand. In addition, we established interactions between hybrid proteins and the flagellin of Salmonella typhimurium by performing surface plasmon resonance (SPR) analysis. The results of the SPR analysis demonstrated notable affinity for both LvLRRm and hybrid proteins towards Salmonella flagellin. The designed LvLRRm hybrid proteins bring insight for universal applications without losing protein functions.

ABC transporter subfamily B1 as a susceptibility determinant of Bombyx mori larvae to Cry1Ba, Cry1Ia and Cry9Da toxins

ATP binding cassette (ABC) transporters are a diverse family of transmembrane proteins. Specific subfamily members expressed in the lepidopteran midgut can act as susceptibility determinants for several insecticidal Bt Cry proteins. However, the susceptibility determinants to many Cry toxins still remain unclear. Therefore, we knocked out a series of ABC transporters that are highly expressed in the midgut of Bombyx mori larvae by transcription activator-like effector nuclease (TALEN)-mediated gene editing, and the lineages that became resistant to Cry toxins were searched by toxin overlay bioassay. As a result, the B. mori ABC transporter subfamily B1 (BmABCB1) knockout lineage showed 19.17-fold resistance to Cry1Ba, 876.2-fold resistance to Cry1Ia, and 29.1-fold resistance to Cry9Da, suggesting that BmABCB1 is the determinant of susceptibility to these toxins. BmABCC2 and BmABCC3 have been shown to be susceptibility determinants based on their function as receptors. Therefore, we next heterologously expressed these ABC transporters in HEK293T cells and performed a cell swelling assay to examine whether these molecules could exert receptor functions. As a result, BmABCB1-expressing cells showed swelling response to Cry1Ia and Cry9Da, and cells expressing PxABCB1, which is the Plutella xylostella ortholog of BmABCB1, showed swelling for Cry1Ba, suggesting that ABCB1 is a susceptibility determinant by functioning as a receptor to these toxins. Furthermore, in order to clarify how high binding affinity is based on receptor function, we performed surface plasmon resonance analysis and found that each KD of Cry1Ba, Cry1Ia, and Cry9Da to BmABCB1 were 7.69 × 10−8 M, 2.19 × 10−9 M, and 4.17 × 10−6 M respectively.

Corrigendum: High performance surface plasmon resonance based sensor using black phosphorus and magnesium oxide adhesion layer

Corrigendum: High performance surface plasmon resonance based sensor using black phosphorus and magnesium oxide adhesion layer

Single-walled carbon nanowires-integrated SPR biosensors: A facile approach for direct detection of exosomal PD-L1

Single-walled carbon nanowires (SWCNWs) possess remarkable mechanical and electronic properties under tension, biocompatibility, π-π stacking interactions with biomolecules, and a large surface area. However, the progress in developing SWCNWs for biosensing applications has been sluggish. This study investigates their potential to improve the performance of surface plasmon resonance (SPR) sensing. Furthermore, the large surface area of SWCNWs allows for high surface coverage of multifunctional peptides at the sensing interface. Through the modification of the SPR sensing interface with multifunctional peptides that combine carbon material affinity, programmed cell death 1 ligand 1 (PD-L1) recognition, and antifouling properties, we have accomplished the highly sensitive, real-time, rapid, and specific label-free detection of exosomal PD-L1 (ExoPD-L1). This work provides a promising new direction for SWCNWs in biosensing applications.

Development of a biosensor based on a surface plasmon resonance structure comprising strontium titanate, graphene and affinity layers for malaria diagnosis

This paper investigates the numerical analysis of a highly performed surface plasmon resonance (SPRE)-based sensor employing a hybrid structure of SrTiO3 (STO) and graphene for rapid detection of malaria. The investigation is performed using the angular interrogation technique and transfer matrix method. The SPRE device has a glass prism, silver (Ag), STO, graphene, affinity layer and sensing medium (SGM). Four coupling prisms are examined and we found the prism N-FK51A corresponds to the highest sensitivity. The sensitivity of the structure N-FK51A/Ag/STO/graphene/affinity layer/SGM is found to be 205.405, 222.222 and [Formula: see text]/RIU for Schizont, Trophozoite and Ring malaria stages. The layer thicknesses are then optimized and it is found that the proposed SPRE sensor can achieve a sensitivity of 278.378, 227.027 and [Formula: see text]/RIU for Schizont, Trophozoite and Ring malaria stages with 30 nm (silver), 1[Formula: see text]nm (STO), mono-sheet of graphene and 5[Formula: see text]nm of the affinity layer. These findings demonstrate that the proposed method and structure can be used efficiently for biomedical applications.

Enhanced detection accuracy and signal-to-noise ratio of surface plasmon resonance based refractive index sensor with the addition of thicker layer of Silicon

The improvement in the sensitivity performance of conventional surface plasmon resonance (SPR) based sensors with the addition of thin layers of various high index dielectrics (e.g. 5 nm–10 nm of Silicon) is well established. This improvement in sensitivity comes at a price of reduced detection accuracy, deteriorated signal-to-noise ratio (SNR) and small value of Figure of Merit (FOM). Sensors with high detection accuracy and SNR find applications in the direct detection of small molecular (few hundreds of Daltons) interactions or low molecular concentrations (physiological concentration) on the surface of the sensor. The current paper presents design methodology and theoretical analysis of the performance of SPR based refractive index sensor with enhanced SNR, detection accuracy, and FOM attained when a thicker layer of Silicon (60 nm–400 nm thickness) is introduced in the conventional Kretschmann configuration employing angular interrogation technique. The analysis is valid for any high index dielectric layer that is used to enhance the electromagnetic field associated with the surface plasmon (SP) mode excited at the metal-dielectric interface. In the present paper, we show that the SP mode which participates in the sensing applications can be excited at the metal-dielectric interface for multiple thicknesses of Silicon. Analytical expressions are derived to compute the multiple thicknesses of Silicon using a modal analysis as well as the transfer matrix method (TMM) by considering the SPR sensor as a multi-layered optical waveguide structure. The refractive index SPR sensor with thicker silicon layer is shown to exhibit a long propagation length and large penetration depth in the analyte region, resulting in a higher depth-to-width ratio (defined as the SNR) and detection accuracy in its SPR reflectivity spectrum, hence enhancing the measurement precision of the sensor.

High performance surface plasmon resonance based sensor using black phosphorus and magnesium oxide adhesion layer

A five-layered Kretschmann configuration-based novel structure is designed for a highly sensitive surface plasmon resonance (SPR) sensor. An adhesion layer of magnesium oxide (MgO) is employed on the BK7 prism to avoid the adverse effects of metallic layers, which cause SPR broadening and a decrease in the resonance magnitude. A few layers of black phosphorus (BP) on top of the silver (Ag) metal layer are added to complete the structure, which becomes the BK7/MgO/Ag/BP configuration. The investigation is carried out using attenuated total reflection (ATR), while the widely used transfer matrix method (TMM) is applied to evaluate the performance of the SPR sensor. A separate analysis is performed using three thicknesses, 5 nm, 10 nm, and 15 nm of MgO, an optimized thickness of 40 nm of Ag, and eight layers of BP. The results revealed that the configuration BK7/MgO (10 nm)/Ag (40 nm)/BP (8 layers) delivers a maximum sensitivity (S) of 234°RIU−1. Moreover, the configuration BK7/MgO (5 nm)/Ag (40 nm)/BP (8 layers) delivers a maximum figure of merit (FOM) of 38.18°RIU−1. With these kinds of extraordinary features, it is expected that the proposed SPR sensor can be applied in different fields of biosensing.

High Resolution and Stability Self-Reference Plasmonic Sensor With Metallic Grating on Multilayered Dielectric Cavity Substrate

In order to improve the sensing performance of surface plasmon resonance (SPR) refractive index (RI) sensor and avoid the negative effect of various environmental factors, a self-reference plasmonic sensor with high resolution and stability based on the combination of metallic grating and multilayered dielectric cavity is proposed in this article. The sensing mode, based on SPR in the metallic grating, is sensitive to the RI variations of the analyte. The guided mode resonances (GMRs), excited by the multilayered dielectric cavity, can be served as self-references due to the insensitivity to the analyte’s RI variations. It is verified that the sensitivity of 500 nm/RIU is achieved, and the smallest sensitivity of self-reference resonance is 0.83 nm/RIU; thus, the sensitivity ratio (stability) is up to 602. Also, a large figure of merit (FOM) of 238 RIU−1 in the sensor is realized and a high-quality factor of 4668 of self-reference mode with high resolution is achieved, which is much better than that of the previous works. The results provide a theoretical basis to design a highly sensitive self-reference plasmonic sensor and have a potential application in the industrial measuring instruments such as the sensor to measure water content in heavy oil.

High throughput-screening of native herbal compounds identifies taccaoside A as a cytotoxic compound that mediates RAS signaling in cancer stem cells

BackgroundCancer stem cells (CSCs) are characterized by their ability to self-renew, to differentiate into multiple cell types and also drive tumor formation, altogether making them important cellular targets for therapeutic intervention. However, existing CSC-targeting drugs do not significantly improve clinical outcomes. More recently, preclinical studies of natural product-derived compounds have demonstrated their potential usefulness as a therapeutic cancer treatment through their cytotoxic actions on CSCs. PurposeHere, we identify CSC-specific compounds derived from natural products and characterize their putative mechanisms of action in CSCs. MethodsGlioblastoma stem cells (GSCs) were labeled with EGFP via homologous recombination and utilized for a high-throughput screen of 8,344 fractions from 386 herbal medicines. The fractions that extinguished EGFP fluorescence signal were then further characterized by LC-MS/MS. Next, several putative cytotoxic compounds were evaluated for their cytotoxic effects on GSCs, cancer cell lines and immortalized cells using a variety of methods to study cell proliferation (EdU incorporation assay), cell death (cleaved-Caspase-3 immunostaining), DNA damage (comet assay), mitochondrial membrane changes (JC-1 immunostaining), and tumor formation in vitro (soft agar colony forming assay). We also performed surface plasmon resonance analysis, western blotting, and immunohistochemistry to characterize the putative mechanisms underlying the cytotoxic effects of putative compounds on GSCs. Finally, we carried out xenograft tumor growth assays to study the cytotoxic potential of several candidates in vivo. ResultsOur high throughput screen led to the identification of the furostanol saponin taccaoside A and its two homologs from the rhizomatous geophyte Tacca. subflabellata that were cytotoxic to GSCs. Interestingly, the cytotoxic effect of taccaoside A on cell lines was significantly less compared to its homologs, owing to stereochemical differences of a carbon–carbon double bond between C-20 and C-22. Molecular studies revealed that taccaoside A binds to RAS to inhibit downstream effector signaling. Correspondingly, blockade of the interaction between taccaoside A and RAS abolished the inhibitory effect of this compound on CSCs. Furthermore, taccaoside A treatment was effective in limiting tumor cell growth in vivo. ConclusionOur study yielded an effective approach to screen for CSC-specific agents. Through this approach, we identified taccaoside A from the rhizomatous geophyte Tacca. subflabellata are cytotoxic to CSCs through a molecular mechanism that involves RAS binding and suppression of its downstream signaling. Our findings indicate taccaoside A is a potential lead compound for anti-CSC drug discovery.

Natural carbazole alkaloid murrayafoline A displays potent anti-neuroinflammatory effect by directly targeting transcription factor Sp1 in LPS-induced microglial cells

Neuroinflammation is a leading cause for neurological disorders. Carbazole alkaloids, isolated from the medicinal plants of Murraya species (Rutaceae), have exhibited wide pharmacological activities particularly for neuroinflammation. However, its underlying cellular targets and molecular mechanisms still remain unclear. In current study, we found that murrayafoline A (MA), a carbazole alkaloid obtained from Murraya tetramera, potently inhibited the production of neuroinflammation mediators, such as nitric oxide (NO), TNF-α, IL-6 and IL-1β in LPS-induced BV-2 microglial cells. Then, we performed thermal proteome profiling (TPP) strategy to identify Specificity protein 1 (Sp1) as a potential cellular target of MA. Moreover, we performed surface plasmon resonance (SPR), cellular thermal shift assay (CETSA) and drug affinity responsive target stability (DRATS) assays to confirm the direct interaction between MA and Sp1. Furthermore, we downregulated Sp1 expression in BV2 cells using siRNA transfection, and observed that Sp1 knockdown significantly antagonized MA-mediated inhibition of neuroinflammation mediator production. Meanwhile, Sp1 knockdown also markedly reversed MA-mediated inactivation of IKKβ/NF-κB and p38/JNK MAPKs pathways. Finally, in vivo studies revealed that MA significantly suppressed the expression of Iba-1, TNF-α, and IL-6, while increased the number of Nissl bodies in the brains of LPS-induced mice. Taken together, our study demonstrated that MA exerted obvious anti-neuroinflammation effect by directly targeting Sp1, thereby inhibiting NF-κB and MAPK signaling pathways. Our findings also provided a promising direction of pharmacological targeting Sp1 for anti-neuroinflammation therapeutics as well as novel agent development.

AB186 Inhibits Migration of Triple-Negative Breast Cancer Cells and Interacts with α-Tubulin.

Breast cancer is one of the leading causes of cancer-related death among females worldwide. A major challenge is to develop innovative therapy in order to treat breast cancer subtypes resistant to current treatment. In the present study, we examined the effects of two Troglitazone derivatives Δ2-TGZ and AB186. Previous studies showed that both compounds induce apoptosis, nevertheless AB186 was a more potent agent. The kinetic of cellular events was investigated by real-time cell analysis system (RTCA) in MCF-7 (hormone dependent) and MDA-MB-231 (triple negative) breast cancer (TNBC) cells, followed by cell morphology analysis by immuno-localization. Both compounds induced a rapid modification of both impedance-based signals and cellular morphology. This process was associated with an inhibition of cell migration measured by wound healing and transwell assays in TNBC MDA-MB-231 and Hs578T cells. In order to identify cytoplasmic targets of AB186, we performed surface plasmon resonance (SPR) and pull-down analyses. Subsequently, 6 cytoskeleton components were identified as potential targets. We further validated α-tubulin as one of the direct targets of AB186. In conclusion, our results suggested that AB186 could be promising to develop novel therapeutic strategies to treat aggressive forms of breast cancer such as TNBC.

Triangular gold nanoplates integrated microgel-based sensor for urinary tract infection and glucosuria detection

A glucose-responsive photonic crystal integrated optical sensor that can detect glucosuria and urinary tract infection was designed by comprehensive numerical analysis. We showed a comparative study of nanoparticle shapes and materials and discussed the performance parameters of the sensor, such as the signal-to-noise ratio, the sensitivity, and the detection limit for various pH levels. Normally distributed nanoparticles were embedded within a functionalized microgel matrix in this proposed structure, and the theoretical study was conducted using the finite element method. Gold was selected as a photonic crystal material due to its nontoxicity and better sensing performance, and triangular-shaped nanoplates were chosen due to their better surface plasmon resonance performance. The sensor showed improved sensitivity of <85.65 nm/mM for pH 7.4, and <110.60 nm/mM for pH 8.0. It depicted a lower detection limit of >0.34 mM for pH 7.4 and >0.30 mM for pH 8.0 than those of previously reported glucose sensor studies. Moreover, the proposed glucose sensor exhibited a practicable signal-to-noise ratio and sensor resolution range. This label-free sensor manifested additional features such as reusability of the sensor, high sensing reversibility, and being readily usable at point-of-care medical facilities.

MRNA-encoded HIV-1 Env trimer ferritin nanoparticles induce monoclonal antibodies that neutralize heterologous HIV-1 isolates in mice.

The success of nucleoside-modified mRNAs in lipid nanoparticles (mRNA-LNP) as COVID-19 vaccines heralded a new era of vaccine development. For HIV-1, multivalent envelope (Env) trimer protein nanoparticles are superior immunogens compared with trimers alone for priming of broadly neutralizing antibody (bnAb) B cell lineages. The successful expression of complex multivalent nanoparticle immunogens with mRNAs has not been demonstrated. Here, we show that mRNAs can encode antigenic Env trimers on ferritin nanoparticles that initiate bnAb precursor B cell expansion and induce serum autologous tier 2 neutralizing activity in bnAb precursor VH + VL knock-in mice. Next-generation sequencing demonstrates acquisition of critical mutations, and monoclonal antibodies that neutralize heterologous HIV-1 isolates are isolated. Thus, mRNA-LNP can encode complex immunogens and may be of use in design of germline-targeting and sequential boosting immunogens for HIV-1 vaccine development.

High-performance fiber-optic-based SPR sensor for DNA hybridization using black phosphorus-tungsten disulfide hybrid structure

A high-performance fiber-optic-based surface plasmon resonance (SPR) sensor is proposed using a hybrid structure of black phosphorus and tungsten disulfide. This study shows the DNA hybridization sensing and the single nucleotide polymorphisms identifying procedure by observing the resonance shift and transmitter power performances for probe deoxyribonucleic acid (DNA), mismatched DNA, and complementary DNA stands. Moreover, the performance parameters, such as sensitivity (S) of 303.43°/RIU, depth-of-figure-of-merit (DFOM) of 760825, quality factor of 121.73 R I U − 1 , and detection accuracy of 3.65 are observed. Finally, this work shows a better SPR performance compared to the state-of-the-art works and includes an additional DFOM parameter, which shows a resonance depth effect.